1. Field of the Invention
The present invention relates to an image forming apparatus having an original conveying apparatus, and, more particularly, it relates to an image forming apparatus having an original conveying apparatus, in which, for example, if a recording sheet is jammed in a main body of the image forming apparatus, non-processed originals conveyed by the original conveying apparatus can easily be re-set.
2. Related Background Art
In the past, in image forming apparatuses such as electrophotographic copying machines, an auto original conveying apparatus (an auto document feeder (ADF)) capable of automatically separating and conveying originals (documents) and setting the original on an original support glass at a predetermined position thereon has widely been used. Since the original can be set without opening and closing a pressure plate of the image forming apparatus, the ADF is presently inevitable for office copying machines in a view point of efficiency of a copying operation.
First of all, an electrophotographic copying machine as an image forming apparatus to which the present invention is concerned will be described.
FIG. 4 is an elevational sectional view of an electrophotographic copying machine to which the present invention is concerned. An original conveying apparatus 50 capable of automatically supplying a plurality of originals is rested on an original support glass plate 1 of a main body 40 of the copying machine.
In FIG. 4, a sheet bundle 15 rested in a cassette 13 is urged against a sheet supply roller (recording sheet supply portion) 16 by means of an intermediate plate 14, so that an uppermost sheet in the sheet bundle is separated by the sheet supply roller 16 and a separation member and the separated sheet is conveyed to a pair of regist rollers 18, where registration of the sheet 15 in a longitudinal direction is adjusted. The original rested on the original support glass plate 1 in a manner described later is illuminated by an illumination lamp 4, and a read image is incident on a photosensitive drum as an electrophotographic photosensitive body (image forming means) 19 through a mirror 3 and a lens 25, thereby forming an electrostatic latent image. The electrostatic latent image is converted into a toner image by a developing device 21 using toner as developing agent. Positions of the toner image and the recording sheet 15 are in a timed relation obtained by the pair of regist rollers 18, and the toner image is transferred onto the sheet 15 at a proper position thereon by means of a transfer roller (transfer means) 20. After the transferring, the sheet 15 is sent, by a convey means 26, to a fixing device 27, where the toner image is heated and fused to be fixed to the sheet 15. Thereafter, the sheet is discharged onto a sheet discharge tray 33 by a pair of discharge rollers 28.
Next, an operation of the ADF (original conveying apparatus) 50 will be briefly described.
As shown in FIG. 4, the originals are rested on an original tray (original resting means) 5 by the operator. In case of the ADF 50, the originals are successively rested on the original tray 5 with imaged surfaces facing downwardly. The first original is nearest the original tray 5. When a lever 29 of an original presence/absence detection sensor is laid laterally by leading ends (tip ends) of the originals, a photo-interrupter (not shown) is blocked, with the result that an original presence signal is sent to a controller as a control device (control means) 60.
In this condition, when a copy button (not shown) is depressed, an intermediate plate 30 is operated by a drive device (not shown) to contact the leading ends of the originals with a supply roller 7. In this condition, when the supply roller 7 is rotated, an uppermost original in the original stack rested on the intermediate plate (and next and/or other original sheet, in some cases) are conveyed to enter into a nip between a separation pad 8 and the supply roller 7. The original supply roller 7 and the separation pad 8 constitute an original supply means.
In this case, the originals other than the uppermost original are stopped by the separation pad 8, with the result that only one original is conveyed to a pair of registration rollers 9a, 9b. The pair of registration rollers 9a, 9b serve to correct skew-feed of the original and to effect registration adjustment. Thereafter, the original is conveyed onto the original support glass plate 1 by an original convey belt 10. When the leading end of the original has passed through a predetermined position on the original support glass plate 1 and reaches an original reverse sensor 31, the original is stopped temporarily, and then is returned by a predetermined amount and then is stopped. This operation is effected, so that, when the original is scanned, the original is correctly positioned on the original support glass plate 1. At this predetermined position, after the original is scanned by an illumination lamp 4 (scan means) such as a halogen lamp mounted on a mirror support (not shown), the original convey belt 10 is operated again to discharge the original onto a discharge tray 32. When a plurality of originals are processed, a subsequent original is supplied while a preceding original is being discharged, and the similar procedures are repeated.
In such an ADF 50, it is assumed that the operator wishes to obtain five sets of copies from three originals by setting the copy number to "5" in an operation portion (not shown).
The operator rests three originals on the original tray 5 of the ADF 50 and depresses a copy start button. As a result, first of all, an uppermost original in the original stack, i.e., a last page (third page) original with imaged surface facing downwardly is urged against the original supply roller 7 by the intermediate plate 30. Then, the original is supplied by the rotation of the original supply roller 7 and then is set at the predetermined position on the original support glass plate 1 by the convey belt 10.
In the present ADF 50, before the optical scanning for the original is started, the subsequent original starts to be supplied, and the subsequent original is waiting while forming a loop therein in front of the pair of registration rollers 9a, 9b. In this condition, the original on the original support glass plate 1 is scanned. The scanning is effected by five times in total for five recording sheets. After the last fifth scanning is finished, when the illumination lamp 4 (including the first mirror support) starts to be shifted in the opposite direction, the original on the original support glass plate 1 is conveyed toward the discharge tray 32 by the rotation of the convey belt 10. At the same time, the subsequent original having the loop and waited at the pair of registration rollers 9a, 9b is conveyed by the rotation of the paired registration rollers 9a, 9b and is reached to the predetermined position on the original support glass plate by the convey belt 10 conveying the preceding original.
The reason for effecting the discharging of the preceding original and the supplying of the subsequent original simultaneously in this way is that the illumination lamp 4 for scanning the original is prevented from being stopped useless at the home position by quickly exchanging the originals. If it takes a long time for exchanging the originals, even when a copying speed of the copying machine (image forming apparatus) 40 is sufficiently high, due to the long exchanging time, the inherent copying speed cannot be utilized completely. It is assumed that the original rested on the original support glass plate 1 is copied continuously. In this case, when the ADF 50 is incorporated into a machine capable of obtaining twelve copies per a minute, if twelve copies can be obtained for each minute, it is said that the copying efficiency is good. However, if an ADF requiring a long original exchanging time is used, the number of copies obtained per minute will be decreased to, for example, ten or nine; this decrease in copying speed is undesirable for the operator.
As mentioned above, after the first original has been supplied, before the first scanning for the original is started, the supplying of the subsequent original and the waiting of the original with the loop at the pair of registration rollers 9a, 9b have already been completed. During the first scanning for the first image, if the sheet 15 to which the first image is to be transferred is jammed in the vicinity of the fixing device 27, the ADF 50 is operated as follows.
First of all, the original on the original support glass plate 1 is conveyed to the discharge tray. Regardless of the jamming in the copying machine, the operator may open the ADF 50. In such a case, since it is not ensured that the original is positioned at the proper location on the original support glass plate 1, even the original which is not yet copied is once discharged. Further, the subsequent original with the loop waiting at the pair of registration rollers 9a, 9b should not be retained at that position because the preceding original must be supplied again from the supply opening of the ADF 50 after the jam treatment, and, thus, the subsequent original must also be discharged, similar to the preceding original.
In this way, if the sheet jam occurs in the machine, both the original on the glass plate which is not yet been copied and the subsequent original waiting at the paired registration rollers are discharged. Although the fact that the original which was already copied was discharged can be recognized by the operator, in many cases, the operator cannot easily understand the fact whether the subsequent original which is not yet been copied is also discharged or not, with the result that the operator worriers about how to set the originals again on the original tray 5 of the ADF 50 after the jam treatment of the main body 40.
Thus, the operator must carefully compare the imaged copies discharged on the discharge tray 33 of the main body 40 with the originals discharged on the discharge tray 32 of the ADF 50 to set the originals again. However, when the subsequent original starts to be supplied after the scanning for copying the preceding original is completed and after the preceding original was discharged, since it takes a long time for exchanging the originals as mentioned above, the copying efficiency is considerably decreased.
As is in the prior art, it was found that any merit cannot substantially be obtained by completing the waiting of the subsequent original immediately after the preceding original is set on the original support glass plate 1. As is in the aforementioned example, when five sets of copies are desired, the supplying of the subsequent original may be started at a timing permitting start of conveyance of the subsequent original immediately before the scanning for the fifth copy is completed and when the discharging of the preceding original is started. With this arrangement, even if the sheet 15 is jammed within the main body 40, the subsequent original remains on the original tray 5. Accordingly, since only the original once set on the original support glass plate 1 is discharged, the operator can easily recognize the discharged original. Thus, after the jam treatment, the original can easily be re-set.